Fix MessagePackObject deserializer cannot handle empty collection correctly. Issue #92.

Return itself when ReadSubtree() just calls duplicatedly. In addition, there is a bug that disposing SubTreeUnpacker twice causes InvalidOperationException. It is just a bug even if the issue #92 was not found.

Author: yfakariya

CHANGES.txt

@@ -277,7 +277,7 @@ Release 0.6.0 Beta3 - 2015/06/14
   BUG FIXES
   * Remove FILETIME dependency to avoid build error in Xamarin/Unity. Issue #87
 
-Release 0.6 - 2015/06/29
+Release 0.6.0 Beta4 - 2015/07/05
 
   BREAKING CHANGES / IMPROVEMENTS
   * Unity3D DLL now only depends on mscorlib.dll. This breaks compabitlity because the library cannot recognize Stack<T>, Queue<T> and NameValueCollection. If you want to these types support, use Unity3D.Full drop instead.
@@ -287,3 +287,6 @@ Release 0.6 - 2015/06/29
 
   BUG FIXES
   * Fix Unity source code to avoid nullable equality operator. Issue #88
+  * Fix MessagePackObject deserializer cannot handle empty collection correctly. Issue #92.
+  * Fix disposing "subtree" Unpacker twice causes Exception.
+

src/MsgPack/SubtreeUnpacker.cs

@@ -51,6 +51,7 @@ internal sealed partial class SubtreeUnpacker : Unpacker
 		private readonly BooleanStack _isMap;
 		private readonly Int64Stack _unpacked;
 		private readonly Int64Stack _itemsCount;
+		private State _state;
 
 		public override long ItemsCount
 		{
@@ -113,24 +114,31 @@ private SubtreeUnpacker( ItemsUnpacker root, SubtreeUnpacker parent )
 				this._unpacked.Push( 0 );
 				this._isMap.Push( root.InternalCollectionType == ItemsUnpacker.CollectionType.Map );
 			}
+
+			this._state = State.InHead;
 		}
 
 		protected override void Dispose( bool disposing )
 		{
 			if ( disposing )
 			{
-				// Drain...
-				while ( this.ReadCore() )
-				{
-					// nop
-				}
-				if ( this._parent != null )
+				if ( this._state != State.Disposed )
 				{
-					this._parent.EndReadSubtree();
-				}
-				else
-				{
-					this._root.EndReadSubtree();
+					// Drain...
+					while ( this.ReadCore() )
+					{
+						// nop
+					}
+					if ( this._parent != null )
+					{
+						this._parent.EndReadSubtree();
+					}
+					else
+					{
+						this._root.EndReadSubtree();
+					}
+
+					this._state = State.Disposed;
 				}
 			}
 
@@ -149,7 +157,13 @@ protected internal override void EndReadSubtree()
 
 		protected override Unpacker ReadSubtreeCore()
 		{
-			if ( this._unpacked.Count == 0 )
+			if ( this._state == State.InHead )
+			{
+				// Duplicate call -- just return me.
+				return this;
+			}
+
+			if ( this._unpacked.Count == 0  )
 			{
 				throw new InvalidOperationException( "This unpacker is located in the tail." );
 			}
@@ -194,6 +208,7 @@ protected override bool ReadCore()
 				}
 			}
 
+			this._state = State.InProgress;
 			return true;
 		}
 
@@ -242,5 +257,12 @@ private void DiscardCompletedStacks()
 				this._unpacked.Push( this._unpacked.Pop() + 1 );
 			}
 		}
+
+		private enum State
+		{
+			InHead = 0,
+			InProgress,
+			Disposed
+		}
 	}
 }

test/MsgPack.UnitTest/Serialization/RegressionTests.cs

@@ -86,5 +86,35 @@ public void TestIssue73()
 				SerializationContext.Default = original;
 			}
 		}
+
+		[Test]
+		public void TestIssue92_EmptyAsMpo()
+		{
+			var bytes = new byte[] { 0x82, 0xA1, 0x74, 0x81, 0xA1, 0x74, 0x04, 0xA4, 0x64, 0x61, 0x74, 0x61, 0x80 };
+			using ( var buffer = new MemoryStream( bytes ) )
+			{
+				var serializer = MessagePackSerializer.Get<Dictionary<string, MessagePackObject>>( new SerializationContext() );
+				var d = serializer.Unpack( buffer );
+			}
+		}
+
+		[Test]
+		public void TestIssue92_EmptyAsCollection()
+		{
+			var value = new int[][] { new[] { 1, 2 }, new int[ 0 ] };
+			var serializer = MessagePackSerializer.Get<int[][]>( new SerializationContext() );
+			using ( var buffer = new MemoryStream() )
+			{
+				serializer.Pack( buffer, value );
+				Console.WriteLine( Binary.ToHexString( buffer.ToArray() ) );
+				buffer.Position = 0;
+				var a = serializer.Unpack( buffer );
+				Assert.That( a.Length, Is.EqualTo( 2 ) );
+				Assert.That( a[ 0 ].Length, Is.EqualTo( 2 ) );
+				Assert.That( a[ 0 ][ 0 ], Is.EqualTo( 1 ) );
+				Assert.That( a[ 0 ][ 1 ], Is.EqualTo( 2 ) );
+				Assert.That( a[ 1 ].Length, Is.EqualTo( 0 ) );
+			}
+		}
 	}
 }